1. Field of the Invention
The invention relates to a reamer having a grinding section with adjustable expansion/contraction and a bore finishing machine comprising the reamer, which are to be employed for finishing of surfaces such as the inner surfaces of cut holes and the inner surfaces of cylinders with high accuracy.
2. Background Art
A reamer having a grindstone section with adjustable expansion/contraction is already known from the specification of U.S. Pat. No. 5,482,498 and from Japanese Utility Model Publication No. Hei 3-29065. According to these documents, the inner peripheral surface of the grindstone section is formed as a tapered surface, a tapered cone or a ball is inserted thereinto, and the tapered cone or the ball is shifted up and down in position with jigs to expand/contract the outer diameter of the grindstone section.
Such adjustment expansion of the diameter with jigs is carried out by hand each time, and the degree of adjustment is slight. A considerable amount of skill is required for the adjustment. It also entails the troublesome process of making several trials of grinding with the diameter-adjusted reamer mounted on the rotation spindle of a grinding machine before final adjustment.